1. Field of the Invention
The invention relates to an automotive ball joint having an elastomeric bearing disposed between a ball head portion of a ball stud and a joint housing. Particularly, the invention relates to the manner in which the bearing is preloaded by the joint housing.
2. Background Art
U.S. Pat. No. 3,650,552 discloses a ball joint having an elastomeric bearing disposed between a joint housing and a ball head portion of a ball stud. The bearing includes two parts, which are disposed at axial opposite ends of the joint housing. An end surface of one of the bearing parts has concentrically arranged rings with a plurality of spring elements formed therein which extend axially away from the bearing part to engage an inner end surface of the joint housing. The spring elements are resiliently deformed during assembly of the ball joint to preload the bearing. Preloading the bearing compensates for production tolerances of the joint parts and wear of the bearing to prevent free play. The resilience of the bearing also permits the absorption of shock. To achieve these results in the known ball joint, the bearing must be of a relatively large volume so that it behaves rigidly in operation, and is provided with the spring elements to axially preload the bearing. Also, the bearing is only loosely engaged on its side surface by the joint housing. The spring elements abuttingly engage the inner surface of the joint housing. Therefore, only a slight amount of relative rotational movement can be transmitted without the bearing moving relative to the joint housing.
German published application No. 1,953,116 discloses a ball joint having a bearing of a hard plastic firmly clamped into the joint housing on one side and which is pressed by small elevations on its end against a shoulder surface of the joint housing. The elevations are deformed plastically in assembling the ball joint and assure a compensation of production tolerances and a relatively uniform contact of the bearing against a ball head. This ball joint is not suitable for absorbing shock. Rather, a shock load leads to further plastic deformation of the elevations, which tends to adversely affect the opertion of the ball joint. To prevent the bearing from rotating in the joint housing, a relatively expensive clamping construction is provided.
German Pat. No. 928,438 discloses a ball joint with an inner bearing which is preloaded against sharp projections arranged in ring form on the inside of the housing cover. In tightening the housing cover to adjust the bearing play, the projections are flattened. Alternating loads of the ball joint lead to the plastic deformation of the projections and cause an increase cf free play in the bearing. Moveover, the bearing is not secured against rotation in the joint housing, so that the operational characteristics of the ball joint vary and increased wear is expected.
It is, threfore, an object of this invention to provide a ball joint having a compact bearing which is prevented from rotation relative to the joint housing, is preloaded to compensate for production tolerances and wear, and absorbs shock loads.